US4149704A - Self-opening closure for the discharge aperture of a crucible - Google Patents

Self-opening closure for the discharge aperture of a crucible Download PDF

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Publication number
US4149704A
US4149704A US05/478,671 US47867174A US4149704A US 4149704 A US4149704 A US 4149704A US 47867174 A US47867174 A US 47867174A US 4149704 A US4149704 A US 4149704A
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United States
Prior art keywords
pellet
closure
crucible
discharge aperture
solid
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Expired - Lifetime
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US05/478,671
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English (en)
Inventor
Dominique de Savigny
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Acieries de Gennevilliers SA
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Acieries de Gennevilliers SA
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K23/00—Alumino-thermic welding

Definitions

  • This invention relates to the discharge aperture of an aluminothermic welding crucible, and particularly to closures for their discharge apertures.
  • aluminothermic welding e.g. thermite welding
  • the principle of aluminothermic welding e.g. thermite welding
  • It consists of using the heat released by the reaction of the formation of alumina from its constituents to obtain the molten welding metal.
  • the reaction being set off by known means such as a localised raising of the temperature.
  • the discharge aperture of the crucible is opened and the welding metal spills out into a crucible which contains the elements for welding.
  • the present invention proposes a self-opening closure which opens at the optimum moment because the opening is conditioned by the temperature of the bath and the end of the reaction. This constitutes an important advantage and makes it possible to overcome, to a certain extent, the disadvantages of the earlier process, for example the differences in the firing times over a batch. In addition this device has the advantage of being adaptable and reproducible.
  • a crucible for aluminothermic welding has at the bottom a discharge aperture closed by a self-opening closure comprising a pellet adapted to be melted by the aluminothermic reaction to open the discharge opening and discharge the contents of the crucible automatically.
  • the present invention proposes a self-opening closure for the discharge aperture of a crucible containing an aluminothermic mixture for welding, the said closure for the discharge aperture consisting of a pellet of a solid which has good mechanical resistance, is not degassed by heating, has a thermal conductivity below 2 kcal/m.h. ° C. and has a fusion temperature below 1600° C.
  • the solid pellet consists of an asbestos pellet, preferably of a CP asbestos board sold by the firm CARTERON, the characteristics of the said board being given below.
  • This CP board contains 98 to 99% asbestos consisting of asbestos fibres from Canada (chrysotile fibres) and is a solid with a density in the region of 1.04, tensile strength of 0.7 kg/mm 2 , a fusion temperature of 1450° C. and a loss in firing by calcination of the order of 15%.
  • This aluminothermic mixing chimney preferably consists of a metal tube covering the solid pellet and filled with aluminothermic mixture.
  • the solid pellet which forms the closure is arranged at the bottom of a metal tube filled with aluminothermic mixture and closed at both ends.
  • the metal tube has thin walls of iron, steel, or preferably of aluminium.
  • This tube will advantageously have a flat base, i.e. it will be a tube of the "aspirin tube” type. The pellet will be deposited on this flat end, the tube will then be filled with the aluminothermic mixture and then closed at the top end, for example by crushing.
  • the discharge aperture of the aluminothermic crucible is a hole drilled in a detachable socket.
  • the discharge aperture drilled in this socket has a part of greater diameter at one end to permit the solid pellet according to the invention to be positioned in the socket on the exterior of the crucible.
  • a crucible provided with a detachable socket is used, as already described;
  • the device which is surmounted by its chimney with the asbestos pellet in the lower part of the chimney, is placed in the socket, that is to say it rests on the part of the discharge aperture drilled in the socket having the greater diameter;
  • a certain thickness of a refractory mixture such as a corundum powder is spread round the aluminothermic mixing chimney in order to insulate the chimney from the lateral walls of the crucible which face it, avoiding covering the upper part of the chimney with the refractory powder;
  • the mass of the proper aluminothermic mixture is then poured into the crucible.
  • this device retains all the advantageous characteristics of a device using a simple pellet and, in addition, the crucibles last as long as the crucibles using the known closing devices.
  • solid having a good mechanical resistance means a solid capable of supporting the charge contained in a crucible for alumonothermy; and the term “not degassable by heating” means a solid which does not give off water vapour when heated, thus which absorbs no or only a little humidity, but which moreover, in aluminothermic conditions, does not decompose or react on the components of the bath while encouraging the formation of gas;
  • the term “low thermal conductivity” means a thermal conductivity below 2 kcal/m.h. ° C. and preferably below 0.5 kcal/m.h. ° C.
  • the fusion temperature of the solid used in the device according to the invention must be below 1600° C. and is preferably between 1300° and 1600° C.
  • One of the principal advantages of the device according to the invention lies in the fact that in the temperature range concerned in aluminothermy there is a substantially linear relationship between the thickness of the solid pellet and the discharging time, which makes it possible to optimise the use of the aluminothermic crucible.
  • FIG. 1 shows a crucible for thermic welding, provided with a discharge device according to the invention
  • FIG. 2 is a graph showing the evolution of the discharging time plotted against the thickness of the pellet for a given charge
  • FIG. 3 shows another embodiment of the device according to the invention
  • FIG. 4 shows a crucible provided with the device according to FIG. 1.
  • FIG. 1 shows a crucible 1 on which is secured, with the aid of a fixing device 3, a raised part 2.
  • the crucible is of a substantially conical shape and consists of three layers, an outer covering 4 the lower part 7 of which has an aperture drilled in it to permit discharging, a refractory lining 6 and an insulating layer 5 between the outer covering and the lining.
  • the lining has drilled in its lower part a conical recess 8 which receives a socket 9 in which a discharge aperture 10 is drilled.
  • This socket has the same conical shape as the recess 8 and can therefore be wedged in the bottom of the crucible.
  • the top end of the discharge aperture 10 has a part of greater diameter 11 which receives the asbestos pellet 12.
  • the part 11 of the discharge aperture 10 is preferably provided with a chamfer on its upper part.
  • the socket 9 can be of silica sand or other refractory material well known in aluminothermic processes, the same as the crucible.
  • the socket When putting the device which has just been described into operation, it was found that in order to obtain good regularity of the discharging times it was necessary for the socket to extend past at least the upper part of the pellet, thus improving the heat transmission from the charge to the asbestos.
  • the welding process using the preceding device is put into operation by known techniques. However, in this particular case it is necessary to take certain precautions: the asbestos pellet is first positioned in the socket before the latter is introduced into the crucible. If the closure between socket and crucible cannot be made tight as a result of wear on the crucible it is necessary to spread a little corundum on the circumference of the cylindrical hole 10. On the other hand it is necessary to ensure that there is no corundum on the top of the asbestos pellet so that the engagement of the closure is not disturbed.
  • FIG. 2 is a graph showing the variations in discharging time in seconds, plotted against the thickness of the pellet in millimeters.
  • the tests were carried out with the crucible of FIG. 1 in which the scale is indicated by the fact that the overall height is 46 cms (including the cylindrical upper part 2).
  • the asbestos pellets are obtained from board of 1100 ⁇ 1000 mm resulting from the overlaying of very fine layers of paste onto asbestos paper, these being deposited after the fibre has been softened in water by punching.
  • the different thicknesses of the pellets necessary for the tests were obtained by wet glueing of two pellets followed by drying.
  • the charge used during these tests is an SO 80 charge containing:
  • the usable range of pellet is between 3 and 8 mm which corresponds to an opening time of between 15 and 27 seconds.
  • the thickness of the pellet is too great, that is to say more than 12 mm, the opening time is too long. Since the metal is close to its solidifying point pouring is difficult and can even be incomplete. The temperature of the filler metal is not sufficient to melt the base metal faces to be welded.
  • the device according to FIG. 3 comprises a detachable socket 21 similar to the socket 9 previously described, and a closure 22.
  • the discharge aperture 23 is drilled in the socket 21 along its axis, the upper end of the aperture having a part of greater diameter 24 serving as a seat for the improved closure.
  • the part with the greater diameter 24 of the socket 21 is preferably provided with a chamfer on its upper part.
  • the closure 22 consists of an aluminium tube 25, cylindrical in shape, its diameter being substantially equal to that of the part 24 of the socket, the said cylinder resting on its flat base 26 in the part 24 of the socket.
  • the asbestos pellet 27 is arranged at the bottom of the cylinder 25 and is covered by an aluminothermic mixture 28.
  • the closure 22 is closed at its upper part 29 by crushing the aluminium tube 25.
  • FIG. 4 shows a crucible 30 of the type described in FIG. 1, having at its lower part the socket 21 provided with the closure 22. After the socket and the closure have been positioned the corundum powder 31 is spread between the lateral walls of the device 22 and the walls of the crucible 30, the positioning of the corundum powder 31 is facilitated by the shape of the upper part 29 of the closure 22, then the crucible 30 is filled with the aluminothermic mixture 32.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Processing Of Solid Wastes (AREA)
  • Furnace Housings, Linings, Walls, And Ceilings (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
US05/478,671 1973-06-20 1974-06-12 Self-opening closure for the discharge aperture of a crucible Expired - Lifetime US4149704A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7322413 1973-06-20
FR7322413A FR2234089B1 (enExample) 1973-06-20 1973-06-20

Publications (1)

Publication Number Publication Date
US4149704A true US4149704A (en) 1979-04-17

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Application Number Title Priority Date Filing Date
US05/478,671 Expired - Lifetime US4149704A (en) 1973-06-20 1974-06-12 Self-opening closure for the discharge aperture of a crucible

Country Status (3)

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US (1) US4149704A (enExample)
ES (1) ES427364A1 (enExample)
FR (1) FR2234089B1 (enExample)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999061194A1 (de) * 1998-05-22 1999-12-02 Ploetz Rolf Transportabler reaktionstiegel für eine metallothermische schweissportion zum einmaligen gebrauch
US6120726A (en) * 1997-10-31 2000-09-19 Elektro-Thermit Gmbh Automatic tapping thimble
US8246715B2 (en) 2010-05-26 2012-08-21 Thut Bruno H Adjustable vortexer apparatus
US9573853B2 (en) 2013-03-15 2017-02-21 Rolls-Royce North American Technologies Inc. Melt infiltration apparatus and method for molten metal control
US9598321B2 (en) 2013-03-15 2017-03-21 Rolls-Royce Corporation Melt infiltration wick attachment
US20190151984A1 (en) * 2017-11-17 2019-05-23 Orgo-Thermit Inc. Rail Welding Crucible and Cap with an Oxygen/Propane Gas Rail-Preheating Burner Ignited Reaction Starter Mix

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3211831C2 (de) * 1982-03-31 1984-01-12 Elektro-Thermit Gmbh, 4300 Essen Selbstöffnender Verscchluß für bei aluminothermischen Reaktionen verwendete Gießtiegel
DE19637282C1 (de) * 1996-09-13 1998-05-20 Elektro Thermit Gmbh Verfahren zum aluminothermischen Zwischengußschweißen von Schienen mit Auflegierung des Stahlgusses im Schienenkopfbereich

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2024132A (en) * 1933-07-06 1935-12-10 Firm Th Goldschmidt A G Process for introducing steel-forming additions into the aluminogenetic iron in aluminothermal welding
US2253364A (en) * 1940-07-27 1941-08-19 Metal & Thermit Corp Ignition of thermit mixtures
US3831915A (en) * 1972-06-22 1974-08-27 Elektro Thermit Gmbh Closure for crucibles used for aluminothermic reactions

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE561364C (de) * 1932-10-13 Aluminothermische Und Elek Sch Tiegel zur Ausfuehrung aluminothermischer Reaktionen, insbesondere fuer Schweisszwecke

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2024132A (en) * 1933-07-06 1935-12-10 Firm Th Goldschmidt A G Process for introducing steel-forming additions into the aluminogenetic iron in aluminothermal welding
US2253364A (en) * 1940-07-27 1941-08-19 Metal & Thermit Corp Ignition of thermit mixtures
US3831915A (en) * 1972-06-22 1974-08-27 Elektro Thermit Gmbh Closure for crucibles used for aluminothermic reactions

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6120726A (en) * 1997-10-31 2000-09-19 Elektro-Thermit Gmbh Automatic tapping thimble
AU765698C (en) * 1998-05-22 2006-09-14 Rolf Plotz Disposable transportable reaction crucible for a metallothermic welding portion
US6484792B1 (en) * 1998-05-22 2002-11-26 Ploetz Rolf Single use transportable reaction crucible for a metallothermic welding portion
CN1108894C (zh) * 1998-05-22 2003-05-21 罗尔夫·普勒茨 用于一个金属热焊接包的一次性使用的便携式反应坩埚
AU765698B2 (en) * 1998-05-22 2003-09-25 Rolf Plotz Disposable transportable reaction crucible for a metallothermic welding portion
RU2220831C2 (ru) * 1998-05-22 2004-01-10 Рольф ПЛЕТЦ Переносной реакционный тигель для порции металлотермитной сварочной смеси для одноразового использования (варианты)
WO1999061194A1 (de) * 1998-05-22 1999-12-02 Ploetz Rolf Transportabler reaktionstiegel für eine metallothermische schweissportion zum einmaligen gebrauch
DE19980928B4 (de) * 1998-05-22 2007-10-31 Plötz, Rolf Transportabler Reaktionstiegel, für eine metallothermische Schweißportion zum einmaligen Gebrauch
US8246715B2 (en) 2010-05-26 2012-08-21 Thut Bruno H Adjustable vortexer apparatus
US9573853B2 (en) 2013-03-15 2017-02-21 Rolls-Royce North American Technologies Inc. Melt infiltration apparatus and method for molten metal control
US9598321B2 (en) 2013-03-15 2017-03-21 Rolls-Royce Corporation Melt infiltration wick attachment
US9884789B2 (en) 2013-03-15 2018-02-06 Rolls-Royce North American Technologies Inc. Melt infiltration apparatus and method for molten metal control
US20190151984A1 (en) * 2017-11-17 2019-05-23 Orgo-Thermit Inc. Rail Welding Crucible and Cap with an Oxygen/Propane Gas Rail-Preheating Burner Ignited Reaction Starter Mix
US10464164B2 (en) * 2017-11-17 2019-11-05 Orgo-Thermit Inc. Rail welding crucible and cap with an oxygen/propane gas rail-preheating burner ignited reaction starter mix

Also Published As

Publication number Publication date
DE2428770A1 (de) 1975-01-09
FR2234089B1 (enExample) 1978-10-27
DE2428770B2 (de) 1977-05-05
FR2234089A1 (enExample) 1975-01-17
ES427364A1 (es) 1976-09-01

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